The liver is the major metabolic organ in the body and secretes a large number of proteins into the blood plasma. Membrane traffic in the secretory and endocytic pathways is also vital to cellular organization and function. The general process of protein transport has been elucidated and is highly similar in the different eukaryotic cell systems studied. The Golgi apparatus is responsible for the sorting and targeting of proteins in transit through these pathways. Recent studies have identified several abundant integral membrane protein species that reside in different compartments of the rat liver Golgi apparatus. These proteins may be essential to the organization and function of the Golgi apparatus, yet no clues are available to their roles. Antibodies raised against two of these liver Golgi membrane proteins recognize specific proteins from whole yeast S. cerevisiae lysates. A growing body of evidence suggests that various aspects of the secretory pathway are functionally conserved in yeast and mammals. The structural similarity of yeast proteins with liver Golgi membrane proteins implies that their functional role in cellular processes may also be conserved. These observations provide tremendous opportunities to investigate the role of these proteins in Golgi apparatus functions with the tools of yeast genetics, molecular and cell biology. The aim of this pilot/feasibility study is to establish the relatedness and nature of the yeast protein homologs and to address initial questions into cellular requirements for their function in Golgi apparatus organization and membrane trafficking pathways.